Process to produce olefins from a catalytically cracked hydrocarbons stream

Abstract

Processes to produce olefins from a hydrocarbons stream obtained from a catalytic cracking unit are described. The process includes the integration of metathesis of C4 olefin process and a hydrocarbon catalytically cracking process to produce commercially valuable products (for example, C2-3 olefins and a C5+ gasoline hydrocarbons).

The invention claimed is: 
     
       1. A process for producing olefins, the process comprising:
 (a) catalytically cracking a hydrocarbons stream consisting essentially of C 5  and C 6  hydrocarbons under conditions sufficient to form a cracked hydrocarbons stream comprising C 5 + gasoline hydrocarbons, and gaseous C 1  to C 4  hydrocarbons; 
 (b) fractionating the cracked hydrocarbons stream to produce at least (1) a first stream comprising C 5 + gasoline hydrocarbons, and (2) a gaseous stream comprising the C 1  to C 4  hydrocarbons and residual C 5 + hydrocarbons; 
 (c) separating the gaseous stream into a gaseous mixed C 4  hydrocarbons stream comprising n-butene and iso-butene, a gaseous C 3  hydrocarbons stream, and a C 5 + gasoline hydrocarbons stream; 
 (d) contacting the gaseous mixed C 4  hydrocarbons stream with a metathesis catalyst under conditions sufficient to produce a second gaseous stream comprising methane, ethylene and/or propylene, and a product stream comprising C 5 + gasoline hydrocarbons; and 
 (e) mixing the step (d) second gaseous stream with the step (c) gaseous C 3  hydrocarbons stream. 
 
     
     
       2. The process of  claim 1 , further comprising mixing the C 5 + gasoline hydrocarbons product stream with the C 5 + gasoline hydrocarbons stream. 
     
     
       3. The process of  claim 1 , wherein separating the gaseous stream of step (c) comprises
 (i) producing a gaseous product stream comprising C1 and C2 hydrocarbons and a gaseous C3+ hydrocarbons stream comprising gaseous mixed C4 hydrocarbons, gaseous C3 hydrocarbons, and residual C5+ gasoline hydrocarbons; and 
 (ii) separating the gaseous C3+ hydrocarbons stream into the gaseous C3 hydrocarbons stream, the gaseous mixed C4 hydrocarbons stream comprising n-butene and iso-butene, and a second C5+ gasoline hydrocarbons stream. 
 
     
     
       4. The process of  claim 3 , wherein the step (a) is performed in a moving catalyst bed. 
     
     
       5. The process of  claim 3 , wherein the catalytic cracking conditions comprise a temperature of 500-700° C. and a pressure of 0.05 MPa to 0.5 MPa. 
     
     
       6. The process of  claim 3 , wherein the catalytic cracking conditions comprise an acidic catalyst. 
     
     
       7. The process of  claim 6 , wherein the acidic catalyst comprises a large pore catalyst. 
     
     
       8. The process of  claim 6 , wherein acidic catalyst is a Y zeolite, an ultra-stable zeolite Y, or a mixture of both. 
     
     
       9. The process of  claim 1 , wherein the step (a) is performed in a catalytic cracker unit comprising a fixed catalyst bed, a moving catalyst bed, or fluidized catalyst bed. 
     
     
       10. The process of  claim 1 , wherein the catalytic cracking conditions comprise water. 
     
     
       11. The process of  claim 1 , wherein the step (d) metathesis conditions comprise a temperature of 200 to 550° C. and a pressure of 0.1 MPa to 2.0 MPa. 
     
     
       12. The process of  claim 1 , wherein the step (d) catalyst comprises a Column 6 metal or compound thereof, a noble metal or a compound thereof, or a combination thereof. 
     
     
       13. The process of  claim 12 , wherein the noble metal is rhenium. 
     
     
       14. The process of  claim 1 , wherein the step (d) catalyst is molybdenum.